Weathercocking simulating means for grounded aviation trainers



June 6, 1950 K. A. KAlL WEATHERCOCKING SIMULATING MEANS FOR GROUNDED AVIATION TRAINERS 4 Sheets-Sheet 1 Filed May 31. 1946 L I M M N 3 m L A R A K Y B a. w 7 Z 6 a 8 q 4H l L m 3 ,I|.|l z

June 6, 1950 K. A. KAIL WEATHERCOCKING SIMULATING MEANS FOR GROUNDED AVIATION TRAINERS 4 Sheets-Sheet 4 Filed Ma 31, 1946' KARL A. KAIL INVENTOR ATTO EYS Patented June 6, 1950 G SIMULATING MEANS FOR GROUNDED" AVIATION TRAINERS;

Karin. Kail,.-Montr.ose; Pa.,- assigner. to LinkAvia tion, 1:10., Binghamton; N; .Y.", a: col-notation: of"

New York.

nil ncsnon lvrw-sr, 1946; semi No;- 37-3593 i oisiins. (01.; 35 m):

This: application: relates: to grounded. aviation:

trainers; andmorepairtieulerly to. means-ion nmuleti-nggi in such trainers thev weatheroocking of a plane-in actual flight. Myinventionwill be disclosed in conjunction with trainers of the type covered by U. Patents-1,825,462-and; 2,099,857.

the; artfthat manyparts oimy: invention may. be adapted. f or use ineeonjnnetion 1 with other types oi trainerss.

In. order that invention;may. be. better. time dersteoxi it is believed thateit. would be. helpful to-;explain-what isrmeant by.weathencocking, and when itooeurs in:theiflyingoiworiealplhne; In the flying of a real plane, a eorreetuturn'ismaw nipulated by coordinated movements. of the oileron. controland rudder. pedals. To startthe turn; ailerons is. first applied. and then. every: small amonntwoi rudder. pedal .use.d;..and-l when the plane: is the turn, it" may. be necessary to. neutralize the. controls. or; even to. ap ly. a small amount. ofoppositeeiiiaron and; rudder; In; a. properly executed turn, the. center line. oi the plane coincides at each... instant. with. the; flight path. of! the plane. In'staki'ng the. plane out of they turn,- opposito rudder. and; aileron are. applied." graduallyend then the controlsv are gradually rec.entered.. The centerline of. the Plane at. all. times should. coincide, in .a, properly executedturn, and in properly comingout' ofthe turn, or very nearly: so, with the flight path;

Howeven. when. a. turn in a plane is made by thez-use'oii rudder pedals onlyggor an;insufiioiency of. coordinated aileron, the plane skids, and

the center line oithe planets: not'pointed along the flight path. Accordingly theplaneis mov ing along at an angle to the'fiight path,- and" if the rudderlnedals are releasedtoo rapidly; the airs-tream. efie'et' upon the tail surfaces; ofithe plane cause the plane: to. turn" momentarily in a; direction .ionpositer the direction of" the turn; so that: the; 'eenten line. oi? the plane aligns itself with. the flight path of.rthe: faulty turn: This adverseturning of the plane is referred to as weathercocking;

It shouldbeparticnlarlynoted' that weather cocking occurs only in the faulty execution of a turn; or the faulty mariiiaulatio'ngof the plane: to taken out of the tixr-n and ocenrs'. only when inordinately large amount" of rudder pedal is. beingusedf V 7 t is a principal object of this: invention to provide means in 7a grounded aviation trainer for siinulatingth'e weethercoekingt effect: (If. a real plane in ctuali night. Iniorder J that the 2;? nature of invention may-w be better: understood, reference ism-aide to -the accompanying drawings, wherein,

Fig. 1 is e, general exteriorview'oftrainerszoi' the type covered by theitwo above mentioned.

UTS. patents. V

Fig. 2:"is. a general -perspeotiveViewshowingthe arrangement within the; trainer of the essential parts orthis invention... 7

Fig. Bis an exploded perspective view'of the rudder-eontrolLvalirei Fig.1: 4 a; general: inersneetiizei' View: oiathe halted. generally by lde jthis... joint being inz turn.

supported;by: the pedestek IE which: rests upon the mains indle as. Spindle lfiis tum row tet'ably mounted: inbase; Hii. The: conventional octagon 22 shown ojsareethe forwardtpitehing biellouazs 2t, the; rearwardmitohing bellows 2 6, the

leitlbenking bellows: 28. andi'the right banking bellows 32;. The-turning; motor is'designated: 30,; anri'the. arms'..-supporting:this:motor by: 34..., The rudderp'edals withinifuselagei i2 are numbered 255; and. the; eontroli wheelffis' fiinfzthis control wheel being held bytthe'shaftl38Whiehisslidably and. rotatabiy mountediwithin: the pedesta-L 40 positioned: to the rear: of i the: instrument. panel 42?. upon. which. are. i'noimtedln plurality of; in struinents M. Asis: well? known to. those; skilled in the art, upone pressingitorward offthei; left: rudder peclal 256.;the turning'motor? 3!): is 'energized to. rotate; the mazin spindle: i8; octasQ 2 2 the pitching. and. i bankingv bellows; the pedestel is; universalijoinh l4. and. fuselage-i2, as well as. the turninggmoton itself tozthe left; about a vertioaliaxise Forward; movement. ofthe right rudder pedal 2% resultsinzansopposite-rotation of; the same: parts: Forward; movement- 0f the Wheel 36resultsiria coliansin 'sof: be o Mand woofer. p-ortimxof: the? in an expansion of bellows 25, and the front end of fuselage I2 is lowered. Opposite movement of wheel 35 results in opposite functioning of the bellows 25 and 26, and the nose of fuselage I2 is raised. A counterclockwise rotation of wheel 35 results in a collapsing of bellows 28 and in an expansion of bellows 32, and the fuselage I2 banks to the left. Opposite movement of wheel 35 results in a contraction of bellows 32 and in an expansion of bellows 28, and fuselage I2 banks to the right. A plurality of steps 98 are provided to enable easy entry to and exit from the fuselage I2, and a seat 28 is provided in the fuselage for the student. A door 59 is provided as is a sliding hood 52, and upon closing of the door and hood, instrument flying conditions may be realistically simulated. A plurality of inspection ports 55 are provided in order that access to the apparatus within the trainer may be easily had. The instruments 55 upon the instrument panel92, as is well known, correspond to the flight instruments of a plane in actual flight, and these instruments properly respond to all fuselage movements as well as to movements of the simulated throttle lever 332 in a manner to simulate the functioning of the instruments of a real plane in response to corresponding plane and throttle lever control movements.

I Simulated rudder loading and trimming means Reference is now made to Fig. 2 which discloses in detail the simulated rudder loading means which may be combined with the novel ing valve designated generally by 219, and. the right rudder control loading bellows 215 is connected by means of the pneumatic line 289 to centering valve 219. It will be noted that the upper rotatable leaf 28I of valve 219 has attached thereto the rear end of the link 282, the forward end of which is pivotally connected to the rudder bar 289.

Reference is now made to Fig. 3 which is a detailed exploded view of the rudder pedal control loading valve designated generally by 219. It will be seen that this valve comprises an upper rotatable leaf or section 28I, a middle rotatable leaf or section I61, and a fixed bottom leaf or section I66.

Fixedly mounted in the center of the lower leaf I66 is the vertical hollow stem I12 having a pluapparatus of this application. In Fig. 2 it will be seen that there is provided a pair of brackets 250, these brackets being afiixed to the inside of the fuselage I2 a substantial distance above the floor at a point ahead of the student's seat 20, as seen in Fig. 1, and a pair of rods 25I are held by the brackets 259. Also pivotally carried by each 'of the rods 25! is a depending squareshaped bracket 259 having mounted in the lower portion thereof a transverse shaft 255 upon each of which is fixedly mounted one of the rudder pedals 255. An arm 252 is affixed to each of the brackets 258, as shown, and pivotally attached to the bottom end of each of the arms 252 is a forwardly extending link 259, the forward end of eacli'of which is pivotally connected to one end of the rudder bar 269 which is pivotally mounted upon the stud 26I carried by the bracket 282 which is fixed to the bottom of the fuselage floor. Afiixed to the left depending arm 252 is the rear end of the forwardly extending rod 255 which is affixed to the rear portion 265 of the left rudder control loading bellows designated generally by 251. It will be seen that this bellows comprises a central member 268 and a forward member 269 as well as the suitable air-tight covering material 219. A hole 289a is drilled through member 268 as shown.

The rod 2' has an enlarged forward end and is fixed to the forward end 269 of bellows 251 by flange 21Ia. The forward end of this rod is pivotally attached to the lower end of the arm 212 carried by the fixed bracket 259. t should be noted that the rear end Z'IIb of the rod 21I passes through the central member 268 of the bellows-281 and telescopes inside the rod 285.

Arod 218, bellows designated generally 215, ro d 215 and arm 211are provided, these parts beingcons'tructed exactly like the corresponding members just described. The left rudder control loading 'b ellowsf261 is connected by means of the pneumatic line1218 to the rudder centerrality of ports I14 in its side walls. Referring now to Fig. 2 it will be seen that the lower end of the hollow stem I12 is connected by means of the vacuum line 283 to the source of vacuum 283a through a conventional step-down regulator bellows 2831). The vacuum within bellows 2832) manifests itself at all times in the central stem In Fig. 3 it will be seen that a pair of vertical ducts I and I86 extend from the upper face of leaf I59 downwardly and partly through the leaf I66. Connecting with the duct I85 is the exterior connector I85a which connects with the line 218 which, as seen in Fig. 2, connects with the left bellows 251. Similarly, connecting with the duct I86 is the connector I88a which connects with the line 288 which connects with the interior of the right bellows 215.

It will be seen that the movable center leaf I61 has a central bore I88 adapted to receive the vertical stem I12 and that two ports I89 and I90 extend completely through the leaf I61. When the leaf I 51 is neutrally positioned relative to the lower fixed leaf I66, the 'port' I89 coincides exactly with the port I85 and the port I98 coincides exactly with the port I86.

In the upper movable leaf 28I are a pair of vertical ducts I9I and I92 which extend completely through the leaf 28L It will be appreciated that the upper ends of both of the ducts I9I and I92 are at all times in communication with the atmosphere. Centrally located within the leaf 28I is the vertical bore I93 extending completely through leaf 28I and adapted to receive the upper end of stem I12 of the lower leaf. Communicating with the vertical bore I93 of leaf 28I is the transverse duct I94 which communicates with the vertical duct I95 drilled in the lower face of the leaf 28L When the three leaves of the valve shown in Fig. 3 are in the neutral position, it w'illbe appreciated that the vacuum in the stem I 12 passes through the ports I14 in the stem into the ducts I94 and I95. In the neutral position there is no overlap between the port I95 in leaf 28I and the ports I89 and I98 in leaf I61, but the port I95 is tangent to the ports I89 and I98 so that a slight amount of vacuum leaks through the two latter ports. At the same time, in the neutral position, the atmosphere which is always present in the ports I9I and I92 cannot pass into either of the ports I89 or I90 because there is no overlap between the ports I9I and I89 on the one hand and ports I92 and I98 on the other. Consequently, when the leaves of the valve 219 are all in their neutral. position, a slight amount of vacuum passes through the lines 218 and 280 into a, we

thebell'owsi. 267 and; 2;! 5;: and the bellows; areneutralized.

However, assuming that. theupper leai28i' is:- rotated counterclockwise from its neutral p0.- siti'on as a result of a. forward movement'of the; rightrudder'pedal 256-, it willbe: appreciated that the. vacuum port [95 will engage the port' I89- which: in the neutral position engages the port" l85'ofthe1ower'leaf 166. At the same time the: atmosphere port I92 will engage the port I90 which; inv theineutralposition engages" the port;

I851 Consequently, an: increased amount of vacuum will: be applied to the line 218 which connects; with the interior of. the: bellows- 261 and. simultaneously atmosphere: will be applied through: the. line. 280 .120: the bellows 215. The bellows. 2.61 willtherefore be contracted: and the bellcwst2l5 will expand. The resultant expanx sion of bellows'2'l5' and. contraction of bellows- 257: will. exert aiforcetending to oppose the forwardimovement of" the right rudder pedal, simulating the efiect ofthe slipstream of: an actual: plane upon its rudder. Ifzthestudents footis' removecl from theright: rudder pedaLthe bellows: 261' and.215 quickly returns both rudder pedalsto tlieirneutral trimmed positions.

On the other hand, it should be understood without a detailed. explanation that when the three leaves of the valve' are in the neutral po sition, a clockwise movement of the upper leaf 2M in response to a pressing forward of the left rudder pedal will apply increased vacuum. to the bellows 2'15 and. atmosphere. to the bellows 1'. Both of the bellows will resist the .movement of the rudder pedals, simulating the slip-- stream effect, and upon releasing of" the stu.-- dents foot from the left rudder pedals, both pedals-will be quickly returned to. their neutral; trimmed positions.v

A capillary is placed in both of thellnes 218 and 28!! to prevent a sudden over-application of vacuum tothe bellows 26? and 275.

It will'be appreciated that whenever the. rudder pedals 256are displaced from their neutral. positions, the fuselage. 12 should rotate with respect to the stationary base luto the left when the. left rudder pedal is forward and to the right when the right rudder pedal is forward. In Fig. 2 it will be seen that the fore end of link- 3H3 is pivotallyconnected to the rudder h-ar zfill whilethe rear end of link 3'l9'i'spiv0tal1y' connected to the lower end of the lever. 1H2 which is pivotally mounted upon the horizontal stub shaft 3M. T0 the upperend of lever 3l'2: is pivo-tally connected: therore end of link M6, the. rear end of which'isrpivotally attached to the outer end? of arm 313 which is fixedly attached to the upper leaf' 329' of the rudder'v-alve desig= nated' generally by 322.

The rudder valve may. be constructed as disclosed in my above mentioned application Serial Number 619,361.01. in the manner of the prior. art. rudder valves. For the purposesof this ap-- plication it issufiicientto know that this. valve has acentral stem .324" connected throughvacuum: lineiezdto' the vacuum source Zttuas wellas a pair ofiports. 328. connected to the turningimotor' as: through vacuum: lines 338. Thisvalve also.

has atmospherctports (not shown) in the? side of. the. upper: leafv 320; Upon a movement-ahead of'the rightjrudder pedal 256' throughlthe memhers 259,.26l;.3lt; 3:!2, M6 and Bit the upper leaf 32E? is rotated" counterclockwise, admitting air and vacuum. to the turning motor which re.- sponds to rotatetfuselage l2 to thexrightl. On:

6 the-. cther. hand, when: the. left rudder: pedal; 256 is.pressedforward:thaupperrleaf is rotated.c1ock-1-- wiseiadmitting. air and vacuum to the turning; m'ctors30 in .a reverseinanner, causing the motor .to: rotate theifuselage to the. left.

With: the apparatus thus far disclosed, when; the rudderxpedalsr-are released they will be returned? by: bGIIOWSx'ZB'I and 215 to their neutral. positionsthe upper leaf 320. will also be returned. tuiits neutral position; and the rotation of the" fuselage will stop.

Under mostflying conditions, most, planes will notffly" perfectly straight with the rudderv pedals: in: the dead centerposition. If the plane isnot equipped: with rudd'ertrimming means it is neeessary" for the pilot to hold the rudder. pedals in'theicorrect position order to keep theplane fiying'a'straight course. Different pressures will have to be applied'under different circumstances. For example, on the take-off itmay be necessary toiapply-a greatdealofv right rudder inorder to keep-the planeflyi'ng straight down the runway. In cruising, left rudder may be necessary; Changesin' engine power and air speed also affect theturning of the plane. In orderto render' it unnecessaryfor the pilot to apply agiven amount of-rudderover a long period of time,.in: order tokeep the. plane-flying the desiredicourse, aircraftof. the type being simulated generally are equippedwithrudder trimming means whereby the plane may be trimmed in order to keep it' flying the desired course without. the pilots. constantly: applying a corrective pressure to the rudder pedals.

In order that this invention may be better; understood, simulated rudder trimming means are also disclosed. herein; Referring. to Fig. 2, the manual. rotation of the rudder trim. knob: 292 causes. a rotation of .theshaft 292 upon the forward end of which is affixed the screw 293.

nut'29 l' coacts with screw 293 to travel longi tudina'lly'thereof.upon a rotation of the screw, and'stud" Zlidtravelsiwiththe nut 29%. A bracket: 2%. is. affixed. to the interior ofthe fuselage l2: and'the lcwer end o'frarin 297i 'ispivotally mounted upontthisbracket. A: horizontal extension 298 is integral with arm129l and pivotally connected. to extension 29B i'sithei upper end of the walking: beam 299. Walking beam 299 is pivotally' mounted on stud 255" as shown. Integral with: thelcwer end of walking beam 299' is the horizontalext'ension 368, andpivotally mounted upon:- the right end of this extension is the arm 30!. Apair'of links 332; and 3% are pivotally attached to'ar m sea as shown. Link 3&2 is connected to: the simulatedthrottle" lever 332 in the trainer: through the arm are, lever 336, compensating." assembly 338', link ttl and arm 339. A pair of dash pots 339s are connected to lever. 336' through their plungers 33% to operate with: spring assemblyfiiw t'o-delay movements of link. 3132 1111 response to movements of lever 332. The; rear end" of link 363 is connected to other ape paratus in thetrainerrespcnsive to the factor of" assumed air speed... For present purposes the? links 332 and see may: be considered stationary, thus providing a fixed pivot for the lower end cfthdwalkingbeam 29! Aihii'ed to the arm as? is the of link;

39 5, tlie forward end of whichlis afilXedlt-c the: uppeifarm: of'hell' crank .23 ll hi The left of link" 3% iispivotally attachedto the lower armoflbell cranktfidhnd the right end of this" link isipivctally attachedito the center leaf l6'l-of.'therrudt'- d'er control: loading valve 279,

2 whenever thestudent in the fuselage finds that he must apply a constant pressure to one of the rudder-pedals inorder to maintain the fuselage upon the desiredheading, it seems clear that the upper leaf 28! of the valve 279 will be displaced from its neutral position and consequently that the bellows ZBTand 275 will exert a constant force tending to return the rudder pedals to their neutral positions. The rudder valve 322 will be positioned so that the fuselage maintains the desired heading. 7

Instead of so positioning the rudder pedals by means of his feet, the student may by rotating the simulated rudder trim control 29!! move the nut 294 in the desired direction. Movement of this nut results in a pivoting of the walkingbeam 299 about its lower end and the arm 29? is pivoted about its'lower end. Link 3% moves inthe correct direction, as does link see, thecenter leaf lfilof the valve 279 rotates in the correct' direction until it is centered with respect to the upper leaf 23 When this point is reached the pressures within the bellows 26? and 275 become quickly neutralized, relieving the pressure upon the rudder pedals, but neither of the bellows is returned to its neutral position. Consequently, the positions of the rudder pedals 255 are not changed and neither are the relative-positions of the leaves of the rudder valve 322. Accordingly, the trainer maintains the desired heading.

Specifically, let us assume that the student in order to maintain the fuselage upon the correct heading finds that he must exert a constant pressure upon the left rudder pedal 256. The upper leaf 28E of the control valve 279 will be rotated clockwise a given distance from its neutral position while the upper leaf 329 of the rudder valve 322 will be rotated a given distance clockwise from its neutral position, Atmosphere will be admitted to the bellows 25'! and vacuum to the bellows 2T5. simulated rudder trim control 29% counterclockwise as seen from above and the not 29 moves toward the head of the fuselage. The middle leaf l6? of the valve 2'39 will be rotated clockwise and when this leaf is centered with respect to the upper leaf 28! the pressure within the two bellows 267 and 215 will become quickly neutralized. The position of the rudder pedals 25$ and of the upper leaf 320 of the rudder valve 322 will be undisturbed with the releasing of the pressure caused by the bellows upon the rudder pedals.

If the student finds he must apply constant right pedal pressure to maintain the fuselage 52 on a constant heading, opposite rotation of the trim control 290 will render the pressure unnecessary.

' Reference is now made to Figs. 2, 4 and for a disclosure of the weathercocking control unit.

In Fig. 2 it will be seen that a block 3% is shown mounted upon the link 3 I 6 and in Fig. 4 it will be seen that screw 342 holds block 346 upon link 3 i 0. A forwardly extending link 34 5 is provided, this link being pivotally held by the pin- 3% which in turn is held by the upper integral extension 3- 38 of block 340. Upon the forward end of link S i l is mounted the compensating assembly designated generally by 850, and referring to Fig. 6 it will be seen that this compensating assembly includes an inner sleeve 352 affixed upon link 3%, and also the outer sleeve 35d which is free to slide with respect to the inner sleeve 352. A stop 35% is mounted upon the foremost end of link 34 3, and spring 358 is provided, this spring encircling the forward end of link 344 and positioned so that The student will then rotate the,

one end bears against the stop-356 while its other end bears against the Washer 359 placedupon link 34 5 between sleeve 354 and the rear end of spring 358. A second stop 360 is afixed upon the link 3% and a second spring 362 is provided, spring 362 also encircling link 34d and arranged so that its front end bears against the washer 35I adjacent the rear end of sleeve 354, while its rear end bears against stop 369. This compensating spring arrangement will be recognized by those skilled in the art as conventional in nature.

The floor of the fuselage i2 is designated l2a, and a base plate 364 is provided, this plate being afiixed to the floor 12a by means of screws 366. Integral with plate 364 is the boss 268 and upon which rests the boss 31D integral with the movable motor carrier 312. Integral with the rear end of member 372 is a second boss 374 positioned vertically above bossS'Hl, and a suitable pivot pin 316 having a head 316a. engaging the upper surface of boss 37d passes through the two bosses integral with carrier 3'12 and into the boss 368 integral with the base member 364, in order that the carrier 372 may pivot with respect to the stationary base member 364 about a vertical axis through pin tit. I-lowe'vena pair of stops 318 are integral with the base member 364 and limit the angular movement of carrier 372 by engagement with the stop 38!) which depends from the lower side of carrier 312.

Integral with the carrier 312 is the raised extension 382. The block 384 is rotatably carried by the forward end of extension 382 by means of the pin 385. The exterior sleeve 354 of the compensating assembly 356 is connected to'the rotatable block 334 by means of pin 388.

A vertical shaft 3953 is rotatably mounted in the boss 392 which depends from the lower side of carrier 3'52, and the right end of arm 3% is freely mounted upon shaft 399, the right end of arm 3% resting upon the top of member 3'52. The left end of arm set is in the form of a fork 396 between the iingers of which is positioned the roller 398 held in place by pin iiifl which in turn is held by th bracket 4G2 integral with the base memher 364.

The .hub 30% of gear 434 is fixed upon shaft 358 by means of pin 493. Referring now also to Fig. 7, it will be seen that the lower surface of gear i-t4 carries the insulating disc MB which in turn carries the two contact segments H2 and did. It will be noted in Fig. '7 that the contact segments M2 and did are separated at MS and Afiixed upon the right end of arm 394 by means of pin are is the contact button arm 422 integral with which is the contact button 524 which always engagesthe lower surface of one or both of the contact segments 452 and Md depending upon their relative rotational positions, as will be later more fully explained.

Integral with the movable motor carrier 372 are the two bosses 412% and 428 which respectively carry'the insulating blocks 430 and 432 which are aflixed thereto by means of screws 436. The insulating blocks 435i carry the brush 438 which is connected through conductor Mil to the terminal 4:52 of motor Md. Insulating blocks s32 carry the brush t lt which is connected through conductor 448 to the terminal 458 f motor 444. The brushes-438 and M5 are held in the same horizontal plane as the contact segments M2 and 4M, brush 438 against the periphery of contact segment di l and brush 446 against the periphery of contact segment M2. The motor M6 is supported-upon the posts 45! which are held by the.

motor base i512 which inturn is attached by screws lli l to the-bosses 426 and428 of the motor carrier 312 The output shaft of motor 444 drives the reduction gears 45% which in turn drive the pinion458; the lower-end of this pinion being ro tatably mounted in the boss 459 integral withthe upper surface of the movablemotor carrier 3-12. Pinion 458 meshes with the gear 46 i to drive the same, as-wellas the elements carried thereby.

The previously described motor and contact control assembly therefor may be arranged so that when the contact button 424* engages both of the contact segments M2 and M4 the motor te l is tie-energized; when the contact bnttonflzs engages only the'conta'ct segment-M 2, motor M4 will be energized to rotatethe g'ear 4M insulating disc 4-1 6* and contact segments clockwise as seen from aboveto again bring both of the contact segments" int engagement with the contact button 626; and when any relative movement between the'contact button and contact segments occurs so that the contact button engages only contact segmental-4, motor M4? is energized to rotate the gear set, insulating disc in and contact segments counterclockwise as seen from above until the; contact button again engages both of the contact segments,

Referring now more particularly to Figs. 2' and 4, itwill be seen that'- there is afiixed upon:

see is pivotally mounted the forwardend of link' 466, the rear end ofwhich is pivotally attached to the upper arm 468 of the bellcrank designated generally by 410. The right end of arm .68- is slotted at 412 and is held by means of set screw 4M upon the upper end of shaft 416 which is held by the base plate 354'. Upon the lower end of shaft 416 is aifixed the forward end of arm 418 by means of set screw 480. The right end of link 482 is pivotally attached to the'rear end of arm 418, and the right end of this link is pivotally attached to the arm 48!; integral with the upper leaf 686 of the weathercocking control valve designated generally by 388.

Reference is now made to Fig. 8 for a detailed disclosure of the construction of the weathercocking control valve. It will be'seen that this valve comprises an upper rotatable section or leaf 4% and a lower section or leaf 4% which has two integral extensions 492 through which the screws 4% pass in order to affix the leaf to any suitable part i212 of the fuselage l2. The upper leaf has a central bore 496 which passes com pletely therethrou'gh and in which the stem 498 having the radial ports 560 is placed. Stem 493 is connected through pneumatic line 562 to thevacuum source 283a. Two atmosphere portsEM and 506 pass completely through the leaf 486, as shown. The port 508- inthe bottom face of leaf 48B is in communication with the ports 500 by means of the channel 5! and port 510a in leaf 486. V r

A pair of ports -5I2 and 514 in the upper face of lower section 49B communicate with the couplings 5E5 and 5!? carried by the lowersection by means of the internal channels 5th and Bit. Recesse's iii-2d and 51130 are also placed inthe upper face of section 490, as shown. Coupling 5| 5 is connected to'one end'of the pneumatic line 529, the other end of which, as seen in Fig. 9, is connected to coupling 522 which connects with the port 52 6 in the front face oftherear section or leaf 524 of the weathercockingshutofi valve designated generally by 528. The section 52shas two integral ears 538 through which the screws 563i pass in order to ailix this section to the plate 532which may be suitably affixed t the trainer fuselage H2. The coupling- 511 in Fig. 8 is' connected through pneumatic line 53 with the coupling 536 in Fig. 9 which communicates with the" port EBS placed in the front surface of section 524. Port 548 is placed-in the front face of section- 52d beside port 526 and is in communication with coupling 5&2 which in turn connects through-the pneumatic line 54 3 with the'turning motor EQ'inFig. 1. At the same time, port 546 is placed in theface' ofsection 524 and communicates with-thecoupling 548 which in turn is connected th'roughpneumatic line 558 withthe turning motor.

A" central vert-icalpost 552 is formed integrally with section 524, and this post is adapted to fit inside the bore efidinthe' rotatable leaf or sec-- tion 5'55 of the weathercocking shuton: valve. A collar EBB-having set'screwsiitil'maybe employed tohold section 556 against the fixed section 524.

In the rear face of the movable section 556 are placedthechannel 562' and the channel 564;

When outer section 558 assumes theopenposntion as shown in Fig; 9; channel- 552' connects'the; ports 538 and- 543- insection 524, and channel 56% connects the" ports- 526 and 540 insection 524. However, whensection 556 is rotated counterclockwise into a different position, it will be ap-' preciated that the flat rear face oft-hissec-- attached by means of pin 518. Pin 512' connects the upper end of link 56%- With the lower-end of the plunger 5% of the'solenoid 576; Guide- 518 may beaiiixed to-the plate 532-, and the solenoid housing eec may similarly be afiixed to member 532. An exten'sion 582 carryingjthe'pin 584' is 1 provided integral with section 525, and a pair' solenoid rotates the leaf counterclockwiseto the" closed position when-the solenoid is energized.

Referring now baclrto Figs. 2 and 3, it will be seen that a bracket 5%: is afiixed upon'the upper rotatable leaf 2B! of the control valve 2'59, and that this bracket carries the micro switch 592'; the movable contact ofwhich carries roller 5%.; Carried by the extension of the center leaf 161' is the pointed stud 596-. The-micro-swit'ch may: be'connected through conductor 598- to a suitable" source of power, and-through the conductor 63c with the solenoid 576 shown in Fig. 9. When the center leaf 1'61 of valve 2l9'is inneutral position with respect to the upper'leaf'ZSI, the'roller 59 i" engages; the point of stud 596' and the microswitch 592 is opened. Accordingly, solenoid'fi'ld is de-energized, plunger 514' is in its down posi-* tion, and section 556 is inits-clockwise position. When section 556 is so positioned channel 562 connects the ports'538and 546, and: channel 56 4 75 connects ports 52!? and 549.

On the other hand, when the upper leaf 28l of the control valve 219 is moved out of neutral position with respect to the center leaf 161, the roller 594 moves out of engagement with the stud 596, micro-switch 592 is closed and solenoid 516 becomes energized. Plunger 514 and link 568 in Fig. 9 move upwardly, rotating section 556 counterclockwise, and shutting off port 538 from port 546 on the one hand, and port 526 from port 548 on the other.

Considering now the operation of the apparatus of this invention, when the rudder pedals 256 in Fig. 6 are in their neutral trimmed positions, leaf 28! of valve 219 will be centered with respect to leaf I61, and micro-switch 592 will be opened. Solenoid 516 in Fig. 9 will be de-energized and valve section 556 will be rotated in its clockwise position bringing ports 538 and 546 on the one hand and 526 and 545 on the other into communication. Assuming that the motor carrier 312 is in its neutralposition with respect to base 364}, as shown in Fig. 2, contact button 425 will engage both of the contact segments 512 and 415 as shown in Fig. 7, and motor 554 will be de-energized. Accordingly, arm 460, link 4 66, bellcrank 410 and link 482 will be in their neutral positions, as will the upper rotatable leaf 488 of the-weathercocking control valve 588. Referring to Fig. 8, when the upper leaf 886 is in its neutral position,it will be appreciated that the port 564 will be offset from the port 512 and the port 566 will be offset from the port 5M. Accordingly, atmosphere will not enter either of the two ports 5|2 or 5M in the lower section 498. Port 568 of the upper section 486 will lie between the two recesses 5|2a and 5l4a of the lower section 465, and a slight amount of vacuum will leak into each of these recesses, and by means of the pneumatic lines 526 and 534 will be applied to the ports 538 and 526 of section 524 of the weathercockingshutofi valve shown in Fig. 9. Accordingly, this slight leak of vacuum may be applied through the pneumatic lines 556 and 545 to the turning motor 30, but as is well understood by those skilled in the art, an equal application of vacuum to both sides of the turning motor will be of no. consequence insofar as turning of the fuselage I2 is concerned.

Then, assuming that the student presses forward the right rudder pedal 256 to turn the fuselage l2 to the right, link Sill in Fig. 2 will be moved ahead, carrying block 3 36 and link- 36 5 in the same direction. Spring 362 will be compressed and will move the sleeve 356 and stud 388,

best seen in Figs. 4 and 5, ahead. By means of block 384 carried by the front end 382 of carrier 312, the entire carrier 312 will be rotated clockwise as seen from above, this rotation taking place about the axis of the vertical pin 316. Accordingly, the vertical shaft 390 is moved clockwise around pin 316, this shaft being kept from rotating by virtue of gear 404 afiixed thereupon and which meshes with the pinion 458. Also the right end of arm 394 moves clockwise about the axis of pin-316, the entire arm sliding somewhat to the right. The entire arm ifiii' will be carried toward the head of fuselage !2, as will'link 266. The movement of link 466 is transferred by means of bellcrank 410 to the link 582, and link 282 will move to the left, resulting in a counterclockwise rotation of the upper leaf 486 of the weathercocking control valve 488; 1 1

Referring to Fig. 8, it will be appreciated that the counterclockwise rotation ofsection'486 of the weathercocking control-valve will bringthe atmosphere port 584 into engagement with port 5I2'in the lower leaf 498, and at the same time vacuum port 508 will bebrought into engagement with the port 5| 4 in' section 498. Accordingly, atmosphere will be applied to the pneumatic line 528 and vacuum to the pneumatic line 535, and referring to Fig; 9, it will be appreciated that atmosphere will be applied to the port 526 in section 524 of the weathercocking shutoff valve 528, while vacuum will be applied to the port 538 in the same section.

However, inasmuch as when the right rudder pedal 256 was moved forward the link 282 in Fig. 2 moves to the rear, rotating the upper section 28! of control valve 219 counterclockwise, it will be appreciated that the roller 594 will move out of engagement with stud 596, resulting in a closing of the micro-switch 592. Accordingly, solehold 516 in Fig. 9 is energized moving plunger 515 and link 568 upwardly, and rotating valve section 556 counterclockwise into the closed position so that the channels 562 and 564 do not connect the ports 538 and 546 and 526 and 540 respectively. Inasmuch as valve section 556 is placed in the closed position, it will be appreciated that the application of vacuum to the port 538 and of atmosphere to the port 5:25 will not affect the turning motor 30. Accordingly, the only response of the turning motor 36 to the pressing forward of the right rudder pedal 256 is the conventional response which occurs as a result of the rotation of the upper leaf 326 of the-main rudder valve 322 in Fig. 2. Accordingly, the trainer turns to the right as though the apparatus of this invention were not included in the trainer. r

Referring now to Figs. 4 and 7,, it will be appreciatedthat when the link 8 34 moves ahead in response to the pressing forward of the right rudder pedal, and the carrier 312 is rotated clockwise about the pin 516, and the right end of arm 595' is moved in the same direction, as seen from above, the contact button 425 will be moved out of engagement with the contact segment 452, but will remain in engagement with thecontact segment 5H3 because of the relative clockwise rotation of the contact segments with respect to the contact button 424. Accordingly, motor 444 will be energized to rotate the gear 405" counterclockwise as seen from above, and this energization of motor 3 35 will continue until the gear 305 and contact segments 342 and 5M have been rotated back into the position at which button 62 3 again engagesboth of them. At this instant motor 4'44 will stop. While motor 555 is rotating-gear 484 counterclockwise as seen from above, it will'be appreciated that the shaft 390 upon which gear 456 is affixed will be rotated in the same direction, and the outer end of arm 56!! will be moved toward the rear of the trainer-in the opposite direction in which it was moved initially in response to the pressing forward of the right rudder pedal. The rearward movement of the outer'endof arm 656 results in a similar movement of link 466, and by means of bellcrank 418 the link 182 is moved towards the right. Accordingly, the upper leaf 48B of the weathercocking control valve is rotated clockwise-the opposite direction in, which it was rotated in response to the initial'rudder pedal movement. At the instant the contact button engages both of the contact segments H2 and 4M, thereby-de-energizing motor 4 34, the upper leaf 586 of the weathercocking control valve 888 is re-centeredyand anequal leak of vacuumwill lage E2 to the left.

2. The micro-switch 592 is closed, solenoid 516 is energized, and the weathercocking shutoff valve 528 is closed.

3. Link 3H3 moves to the rear carrying link 344 therewith, and rotating the motor carrier 312 and shaft 396 counterclockwise about the axis of pin 316, resulting in a movement to the rear of arm 468 and link 466, and through the action of bellcrank 478 a movement to the right of link 482 and a clockwise rotation of the upper leaf 486 of the weathercocking valve 488. Atmosphere is applied to pneumatic line 534 and vacuum to line 520, but inasmuch as the weathercocking shutoff valve 528 is closed, 110 auxiliary turning effect occurs. V

4. The angular movement between the contact segments M2 and 4! with respect to contact button 424 energizes motor 444 to turn the gear 4% and contact segments clockwise as seen from above, resulting in a similar rotation of shaft 390 and a return movement of link 466 to its neutral position, thereby returning the upper leaf 486 of the weathercocking control valve 488 to its neutral position, and equalizing the pressure within the pneumatic lines 526 and 534 which go to the weathercocking shutoff, valve .528. However, it should be noted that the motor carrier 312 and shaft 398 continue to be displacedcounterclockwise of their neutral positions. 7

5. Assuminglthat after an elapse of a predetermined length oftime, during which the fuselage l2 continues to rotate to-the left, the student takes the fuselage out of the turn to the left by quickly releasing the left rudder pedal, the rudder pedals will be quickly returned to their neutral positions, and the motor carrier 312 and shaft 396 will be rotated clockwise so that the motor carrier and the axis of shaft-398 assume their neutral positions as seen in Fig. 2. Accordingly, arm 460 will move ahead and through the interconnecting linkage system the upper leaf 486 of the weathercocking control valve 488 will be rotated counterclockwise of its neutral position, applying atmosphere to line 534 and vacuum to line 520. a

6. The micro-switch 592 will beopened, deenergizing solenoid 516, and the upper leaf 556 of theweathercocking shutoff valve will be rotated counterclockwise by spring 596 into the open position. H v Y '7. Atmosphere'will be applied to the pneumatic line 559 and vacuum to the pneumatic line d4, and the turningmotor 35 will respondto rotate the fuselage 12 toward the right. l

8. The returning of motor carrier 312 toit neutral position will result in an angular movement between the contact segments M2 and 4M with respect to contact button 424-, and motor 444 will be energized to rotate gear 404, the contact segments and shaft 396 counterclockwise as seen from abOVe, shaft330 will be rotated in thesame direction and through the interconnecting linkages'the upper leaf 586 of the weathercocking control valve will be gradually "returned to its neutral position, gradually neutralizing the pressure within lines 520 and 534, and gradually reducing the rate of turning of fuselage -|2 to the right. 7 Motor dds will" continue to be energized until the entire-- apparatus is returned-to itsneu' "-16 tral position, whereupon the turning of fuselage l2 toward the right will cease.

If instead of quickly releasing the left rudder pedal, the student gradually releases the same, the micro-switch 596 will not be opened until the rudder pedals are returned to their neutral trimmed positions, at which time the motor 444, energized by the gradual return of carrier 312 to its neutral position, will have returned the upper leaf 386 of the weathencocking control valve to its neutral position, and consequently no auxiliary turning of the fuselage 2 to the right will occur.

It is believed unnecessary to further explain the operation of the apparatus of this invention when the student applies coordinated aileron and rudder to cause the fuselage to start to turn in a given direction, then slowly neutralizes the rudder (or even applies a slight amount of opposite rudder) to maintain the proper rate of turn, and then to bring the fuselage out of the turn, slowly applies opposite rudder or additional opposite rudder, as the case may be, and finally, slowly centers the rudder pedals. The previous explanation of the operation of the apparatus should sufiice, because such a series of manipulations is merely combined right and left rudder movements, both of which have been explained.

In view of the above disclosure, it will be appreciated that the apparatus of this invention functions in a manner to reproduce the weathercocking effect of a plane in actual flight when the trainer is flown in a manner corresponding to the flying of a real plane which would produce a weathercocking effect. When the con trols in the fuselage are properly manipulated in executing a turn of the fuselage, the rudder pedals 256 will only be displaced by a limited amount, and they will always be slowly displaced and slowly returned to their neutral positions. Accordingly, the apparatusof this invention will not produce any weathercocking effect. How.- ever, whenever a large amount of rudder is employed in executing a turn in the trainer, if the rudder is not very gradually released a weathercocking effect will occur, just as in the case of a plane in actual flight.

It will be appreciated that many changes may be made in the disclosed embodiment of my invention, and accordingly, the disclosed embodiment should be considered as illustrative rather than limiting in nature. The following claims are intended to include all such changes.

I claim:

1. In a grounded aviation trainer of the type including a fuselage rotatably mounted upon a stationary base, the combination of a motor arranged to rotate the fuselage, rudder pedal means in the fuselage, a first means interconnesting the rudder pedal means and the motor for actuating the motor to turn the fuselage in a predetermined direction in response to the application of pressure to the rudder pedal means, and additionai means interconnecting said rudder pedal means and said motor and operable upon a relatively rapid releasing of the pressure upon the rudder pedal means to actuate the motor to cause the fuselage to turn in the opposite direction for a predetermined length of time, said additional means comprising a control operated by a releasing of the pressure upon the rudder pedal means for regulating the actuation of the motor, and follow-up means operated by a releasing ofthe pressure upon the 17 rudder pedal means for regulating the control.

2. In a grounded aviation trainer of the type including a fuselage rotatably mounted upon a stationary base, the combination of a motor arranged to rotate the fuselage, rudder pedal means in the fuselage, a first means intercomnecting the rudder pedal means and the motor for actuating the motor to turn the fuselage in a predetermined direction in response to the ap plication of pressure to the rudder pedal means, and additional means interconnecting said rudder pedal means and said motor and operable upon a relatively rapid releasing of the pressure upon the rudder pedal means to actuate the motor to cause the fuselage to turn in the opposite direction at a gradually reducing rate and for a predetermined length of time, said. additional means comprising a control operated by a releasing of the pressure upon the rudder pedal means for regulating the actuation of the motor, and follow-up means operated by a releasing of the pressure upon the rudder pedal means for regulating the control.

3. In a grounded aviation trainer of the type including a fuselage rotatably mounted upon a stationary base, the combination of a motor arranged to rotate the fuselage, rudder pedal means in the fuselage, means for automatically returning said rudder pedal means to predetermined neutral position upon the releasing of a manually applied pres-stu'e thereto, a first means interconnecting the rudder pedal means and the motor for actuating the motor to turn the fuselage in a predetermined direction in response to the application of pressure to the rudder pedal means, and additional means interconnecting said rudder pedal means and said motor and operable in response to the operation of said rudder pedal returning means as a result of a relatively rapid releasing of the manual pressure upon the rudder pedal means for actuating said motor to cause the fuselage to turn in the opposite direction for a predetermined length of time, said. additional means comprising a control operated by the returning of the rudder pedal means to the neutral position for regulating the actuation of the motor, and follow-up means operated by the returning of the rudder pedal means to the neutral position for regulating the control.

4. In a grounded aviation trainer of the type including a fuselage rotatably mounted upon a stationary base, the combination of a pneumatically operated motor arranged to rotate the fuselage, rudder pedal means in the fuselage, means interconnecting the rudder pedal means and the motor for actuating the motor to turn the fuselage in a predetermined direction in response to a displacement of the rudder pedal means from the neutral position, and means operable upon a relatively rapid recentering of the rudder pedal means to cause the fuselage to turn in the opposite direction for a predetermined length of time, said last means comprising a valve connected to said pneumatically operated motor, a follow-up motor connected to the valve, control means for the follow-up motor, a connection from the rudder pedal means differentially combined with the connection between the follow-up motor and the valve for actuating the valve upon recentering of the rudder pedal means, and a connection between the rudder pedal means and follow-up motor control means for actuating the follow-up motor upon a recentering of the rudder pedal means.

KARL A. KAIL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,358,016 Link et al Sept. 12, 1944 2,385,095 McCarthy Sept. 18, 1945 

